Berbamine sensitizes hepatocellular carcinoma to chemotherapy by inhibiting autophagy via modulating SIRT1-mediated acetylation

Chemoresistance driven by pro-survival autophagy remains a major obstacle in hepatocellular carcinoma (HCC) treatment. Berbamine (BBM), a natural alkaloid with a favorable clinical safety profile, shows potential as an autophagy inhibitor, yet its precise mechanism in HCC remains unclear. Using CCK-8, colony formation, and apoptosis assays, we first demonstrated that BBM synergistically enhanced the efficacy of multiple chemotherapeutic agents (5-FU, Sorafenib, Paclitaxel) against HCC cells in vitro . This synergistic effect was confirmed in an H22 xenograft mouse model in vivo . To investigate the mechanism, we monitored autophagic flux and lysosomal function. Western blot and immunofluorescence analyses revealed that BBM treatment led to the concurrent accumulation of LC3-II and p62, indicating a blockade of late-stage autophagic flux. Further experiments, including LysoTracker staining and assessment of lysosomal protease levels, showed that BBM impaired both autophagosome-lysosome fusion and lysosomal acidification. Mechanistically, we found that BBM downregulated SIRT1 protein expression and reduced the intracellular NAD + /NADH ratio, thereby inhibiting SIRT1 deacetylase activity. This suppression impaired the nuclear translocation and function of the key autophagy transcription factor TFEB, leading to decreased levels of its downstream targets RAB7, CTSB, and CTSD. Crucially, rescue experiments using specific agonists revealed that SIRT1 activation completely reversed all BBM-induced effects, including autophagic flux blockade and downstream protein suppression, whereas TFEB activation only partially rescued the expression of RAB7, CTSB, and CTSD without restoring autophagic flux. This establishes SIRT1 as the primary upstream regulator in this pathway. Our study identifies BBM as a novel autophagy inhibitor that targets the SIRT1-TFEB axis to disrupt autolysosomal fusion and degradation, and nominates it as a promising combinational agent to overcome chemoresistance in HCC.